The present invention relates to a non-asbestos friction composition having made it possible to manufacture the mold type facing and pad lining using aramid fiber pulp and inorganic fibers in dry process.
In the manufacture of asbsestos friction materials for brake or clutch with mold, the formulated mix has been molded preliminarily with prepress as a pretreatment in the hot press process. This prepress process could be carried out in all ways of dry and wet process because of the lack of spring back characteristic in asbestos.
In recent years when the regulation of asbestos has been strengthened and asbestos cannot be formulated into the friction materials, it is requested to use the fibers with high heat resistance and high reinforcement property, which are important factors having been performed with asbestos in the friction materials, as substitutes.
There, as the substitutes of this asbestos, use of glass fibers, aramid fibers, mineral fibers, natural fibers, etc. is tried and the friction materials used these fibers are known in, for example, U.S. Pat. No. 3967037, No. 4373038, No. 4465796, etc. However, all of the fibers aforementioned cannot be molded preliminarily in dry process because of large spring back. Therefore, it is a present status that the preliminary molding cannot help but rely entirely on wet manufacturing process utilized the adhesive force of solution.
However, the manufacture in wet process is undersirable since it has an advantage to suppress the spring back of said fibers, but, on the other hand, there are rising in expenses due to the use of solvent and the addition of drying process and an anxiety in the obstruction of workers health by solvent. The invention has been made to dissolve these problems.